--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/VirtualMailManager/ext/postconf.py	Thu Jun 28 19:26:50 2012 +0000
@@ -0,0 +1,127 @@
+# -*- coding: UTF-8 -*-
+# Copyright (c) 2008 - 2012, Pascal Volk
+# See COPYING for distribution information.
+"""
+    VirtualMailManager.ext.postconf
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Wrapper class for Postfix's postconf.
+    Postconf instances can be used to read actual values of configuration
+    parameters or edit the value of a configuration parameter.
+
+    postconf.read(parameter) -> value
+    postconf.edit(parameter, value)
+"""
+
+import re
+from subprocess import Popen, PIPE
+
+from VirtualMailManager.errors import VMMError
+from VirtualMailManager.constants import VMM_ERROR
+
+_ = lambda msg: msg
+
+
+class Postconf(object):
+    """Wrapper class for Postfix's postconf."""
+    __slots__ = ('_bin', '_val')
+    _parameter_re = re.compile(r'^\w+$')
+    _variables_re = re.compile(r'\$\b\w+\b')
+
+    def __init__(self, postconf_bin):
+        """Creates a new Postconf instance.
+
+        Argument:
+
+        `postconf_bin` : str
+          absolute path to the Postfix postconf binary.
+        """
+        self._bin = postconf_bin
+        self._val = ''
+
+    def edit(self, parameter, value):
+        """Set the `parameter`'s value to `value`.
+
+        Arguments:
+
+        `parameter` : str
+          the name of a Postfix configuration parameter
+        `value` : str
+          the parameter's new value.
+        """
+        self._check_parameter(parameter)
+        stderr = Popen((self._bin, '-e', parameter + '=' + str(value)),
+                       stderr=PIPE).communicate()[1]
+        if stderr:
+            raise VMMError(stderr.strip(), VMM_ERROR)
+
+    def read(self, parameter, expand_vars=True):
+        """Returns the parameters value.
+
+        If expand_vars is True (default), all variables in the value will be
+        expanded:
+        e.g. mydestination: mail.example.com, localhost.example.com, localhost
+        Otherwise the value may contain one or more variables.
+        e.g. mydestination: $myhostname, localhost.$mydomain, localhost
+
+        Arguments:
+
+        `parameter` : str
+          the name of a Postfix configuration parameter.
+        `expand_vars` : bool
+          indicates if variables should be expanded or not, default True
+        """
+        self._check_parameter(parameter)
+        self._val = self._read(parameter)
+        if expand_vars:
+            self._expand_vars()
+        return self._val
+
+    def _check_parameter(self, parameter):
+        """Check that the `parameter` looks like a configuration parameter.
+        If not, a VMMError will be raised."""
+        if not self.__class__._parameter_re.match(parameter):
+            raise VMMError(_(u"The value '%s' does not look like a valid "
+                             u"postfix configuration parameter name.") %
+                           parameter, VMM_ERROR)
+
+    def _expand_vars(self):
+        """Expand the $variables in self._val to their values."""
+        while True:
+            pvars = set(self.__class__._variables_re.findall(self._val))
+            if not pvars:
+                break
+            if len(pvars) > 1:
+                self._expand_multi_vars(self._read_multi(pvars))
+                continue
+            pvars = pvars.pop()
+            self._val = self._val.replace(pvars, self._read(pvars[1:]))
+
+    def _expand_multi_vars(self, old_new):
+        """Replace all $vars in self._val with their values."""
+        for old, new in old_new.iteritems():
+            self._val = self._val.replace('$' + old, new)
+
+    def _read(self, parameter):
+        """Ask postconf for the value of a single configuration parameter."""
+        stdout, stderr = Popen([self._bin, '-h', parameter], stdout=PIPE,
+                               stderr=PIPE).communicate()
+        if stderr:
+            raise VMMError(stderr.strip(), VMM_ERROR)
+        return stdout.strip()
+
+    def _read_multi(self, parameters):
+        """Ask postconf for multiple configuration parameters. Returns a dict
+        parameter: value items."""
+        cmd = [self._bin]
+        cmd.extend(parameter[1:] for parameter in parameters)
+        stdout, stderr = Popen(cmd, stdout=PIPE, stderr=PIPE).communicate()
+        if stderr:
+            raise VMMError(stderr.strip(), VMM_ERROR)
+        par_val = {}
+        for line in stdout.splitlines():
+            par, val = line.split(' = ')
+            par_val[par] = val
+        return par_val
+
+del _